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© Boardworks Ltd 2003

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Leaves are like small factories that produce food for the plant. Different parts of the leaf have different jobs. The veins in a leaf are bundles of tiny tubes that carry water and minerals to the leaf and return food from the leaf to the rest of the plant. Veins also help to support the leaf.

Leaves

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Leaves

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Leaves are green because they contain small bodies in the cells called chloroplasts. The chloroplasts contain a green pigment called chlorophyll. This green material gives the leaf its colour.

With the help of chlorophyll and energy from the sun, a leaf can change lifeless substances into food. This process is called photosynthesis. Plants need water (H2O) and carbon dioxide (CO2) to make food through the process of photosynthesis. The water is gathered by the plant's roots. Carbon dioxide is gathered from the air through the stomata.

Photosynthesis

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The leaf uses chlorophyll and sunlight to change the water and carbon dioxide into oxygen and glucose (sugar). This sugar is mixed with water and sent to other parts of the plant to be used by the plant as food. The oxygen is released into the air through the stomata. This is usually written as:

Carbon + water Glucose + oxygen

This is usually read as carbon dioxide plus water in the presence of light and chlorophyll produces oxygen and sugar glucose.

Light

Chlorophyll

Photosynthesis (continued)

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Chloroplast

These are small structures that vary in number and size.

They contain a green pigment called chlorophyll.

Chlorophyll

LIGHT

The chlorophyll traps sunlight and uses this energy to drive the

process of photosynthesis.

Photosynthesis is the name of the chemical reaction that produces the

plant’s food.

Therefore, Chloroplasts are where a plant makes its own food.

Photosynthesis summary

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Photosynthesis activity

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Photosynthesis

FOOD (GLUCOSE)

OXYGEN+ + ENERGYWATERCARBON DIOXIDE +

We know that plants make their own food from sunlight. They are the producers in the food chain. This is done in the green parts of the plant, e.g. upper surface of the leaves. The reaction for this is:

Made byphotosynthesis and stored

as starch in leaves, roots,

stems, etc.

Taken in through holes in the

leaves

USEFUL!waste product exhaled

Taken in through the roots

With light and

chlorophyll

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Roots

The roots of a plant provide:

• A way of getting water from the ground.

• Stability for the plant by anchoring it into the ground.

The water absorbed by the plant is used for:

• Photosynthesis.

• Keeping the plant rigid (turgidity)

• All the chemical reactions in the plant

• To move dissolved minerals (nitrates) to cells

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